After a nearly 10,000-year gruelling battle with the demons Madhu and Kaitabha, Vishnu was exhausted. He could not even bring himself to get up or lay down for a bit of rest. He fell asleep on his bow, his head perched precariously and yet comfortably on its string. His body slumped over the bow, was wrapped in an unshakeable stupor.
A sleeping Vishnu was a bad omen. But none dared to break his nidra, neither Shiva nor Brahma nor could any of the gods dare to disturb the sleep of the divine goddess Yoganidra. But something had to be done so Brahma decided to seek the help of the vamsis (white ants). He asked them to gnaw at the string so that it would break and wake up the sleeping Vishnu.